Hitherto, from the viewpoint of energy conservation represented by the reduction of cooling load, there has been a social stream toward reducing the effect of infrared rays as much as possible. Such stream tends to be increased more and more due to the increase of interest about global warming phenomena and environmental problems and the like. This stream brings about various changes to glass industry. By providing glass itself or the glass surface with the absorption function and the reflection function, glasses that reduce the effect of infrared rays have been developed, and they have been commercialized as infrared absorptive glasses or infrared reflective glasses.
There is known a soda-lime-silica glass (see Patent Publication 1) that has a composition comprising by weight % 66-75% SiO2, 12-20% Na2O, 7-12% CaO, 0-5% MgO, 0-4% Al2O3, 0-3% K2O, 0-1% Fe2O3, and 0-1.5% of the total of CeO2, TiO2, V2O5 or MoO3, that is a glass article in which the total iron is in at least 0.45 weight %, and its 35% or greater is of an iron that is in the ferrous iron condition represented by FeO, and less than 0.02 weight % of sulfur expressed as SO3 is contained, and that is of an infrared absorptive type showing a visible light transmittance (400-770 nm) of at least 65% and an infrared transmittance (800-2100 nm) of not greater than 15%.
There is a social movement towards reducing the effect of ultraviolet rays as much as possible, such as ultraviolet deterioration of organic materials represented by fading phenomena and the occurrence of skin cancer by ultraviolet irradiation. In view of such movement, there is a study of a commercial product that reduces the effect of ultraviolet rays by providing the glass itself or the glass surface with the ultraviolet absorptive function and reflective function. Its representative example is ultraviolet absorptive glass.
There is known an ultraviolet absorptive colored glass (see Patent Publication 2) which has a composition substantially comprising by weight % 65-75% SiO2, 0.1-5 Al2O3, 10-18% Na2O, 0-5% K2O, 5-15% CaO, 1-6% MgO, 0.05-1.0% SO3, 0.2-1.5% Ce moiety in terms of CeO2, 0-1.0% Ti moiety in terms of TiO2, 0.001-0.006% CoO, 0.3-1.6% Fe moiety in terms of Fe2O3, and in which 5-18 wt % of the Fe moiety in terms of Fe2O3 is of Fe2+.
There are described in this patent publication that the dominant wavelength measured with C light source is 488-492 nm and the color purity is 3-4%, that the visible light transmittance measured at a thickness of 3-5 mm with A light source is 70% or greater, that the ultraviolet transmittance defined in ISO is 15% or less, that, if the content of CoO is less than 0.001%, the dominant wavelength becomes too long, thereby having a yellow color tone, and that, if it is greater than 0.006%, the dominant wavelength becomes too short, thereby not obtaining a bluish glass.
Furthermore, it has changed to a stream to simultaneously reduce the effect by ultraviolet rays and the effect by infrared rays. This stream is in a direction to increase more and more due to the increased interest in global warming phenomena and environmental problems and the like. In this stream, a so-called ultraviolet and infrared absorptive glass that absorbs both of ultraviolet rays and infrared rays attracts attention, in addition to conventional infrared absorptive glass and ultraviolet absorptive glass.
There is disclosed an infrared and ultraviolet absorptive, soda-lime-silica, greenish glass (see Patent Publication 3), which contains as major components 0.65-1.25 wt % Fe in terms of Fe2O3, 0.2-1.4 wt % CeO2 or 0.1-1.36 wt % CeO2 and 0.02-0.85 wt % TiO2, and in which the weight ratio of FeO to Fe2O3 is fixed to have at a thickness of 3-5 mm an Illuminant A visible light (wavelength 400-770 nm) of 70% or greater, a total solar energy (wavelength: 300-2130 nm) transmittance of 46% or less and an ultraviolet (wavelength 300-400 nm) transmittance of 38% or less.
There are described in this patent publication that the above Fe is 0.48-0.92 wt % Fe2O3 and 0.15-0.33 wt % FeO, that the weight % of FeO constitutes a reduction percent of 23-29% of the total iron content expressed as Fe2O3, that Illuminant C dominant wavelength is 498-525 nm, that the color purity is 2-4%, and that 65-75 wt % SiO2, 10-15 wt % Na2O, 0-4 wt % K2O, 1-5 wt % MgO, 5-15 wt % CaO and 0-3 wt % Al2O3 are contained.
There is disclosed an infrared and ultraviolet absorptive glass (see Patent Publication 4), which substantially comprises in terms of oxide 65-75 wt % SiO2, 0.1-5 wt % Al2O3, 10-18 wt % Na2O, 0-5 wt % K2O, 5-15 wt % CaO, 1-6 wt % MgO, 0.1-3 wt % CeO2, 0.5-1.2 wt % Fe2O3, 0.05-1.0 wt % SO3, and 0-1.0 wt % TiO2, and in which 20-40% by weight of the total iron content expressed as Fe2O3 are in ferrous iron (FeO).
There are described in this patent publication that a coloring agent may be added to the glass of the above-mentioned compositional range to the extent that the total amount of one kind or two kinds or more of NiO, CoO, MnO, V2O5, MoO3 and the like is in 0-1.5 wt %, that according to need 0-3 wt % of ZnO may be added in order to prevent deterioration of color tone by ultraviolet rays and coloring of amber, and that the visible transmittance (380-780 nm) is 66.1-66.8%, the solar heat transmittance (340-1800 nm) is 37.7-38.4%, and the dominant wavelength is 501-503 nm (green color) at 5 mm in thickness in examples.
There is disclosed an ultraviolet and infrared absorptive glass (see Patent Publication 5) which has a composition of 65-75% SiO2, 0-5% Al2O3, 10-18% Na2O, 0-5% K2O, 5-15% CaO, 0-5% MgO, 0.1-3% CeO2, 0.2-1% FeO, and 0.1-3% SnO2 in weight %, which contains 0-1.5% of a coloring agent such as NiO, CoO, MnO, V2O5, MoO3 and the like, 0-3% ZnO, and 0.1-3% SnO2, and in which the dominant wavelength is 488-497 nm.
The present applicant also discloses an ultraviolet and infrared absorptive greenish glass (see Patent Publication 6) which contains by weight % 67-75% SiO2, 0.05-5% Al2O3, 12-16% Na2O, 0.5-3% K2O, 7-11% CaO, 2-4.2% MgO, 0.05-0.3% SO3, 1.0-2.5% CeO2, 0.1-1.0% TiO2, 0.0010-0.0400% MnO, 0.0001-0.0009% CoO, and 0-1% SnO2, and which has a composition of 70-76% of SiO2+Al2O3+TiO2, 10-15% of CaO+MgO, and 13-17% of Na2O+K2O.
Furthermore, even in the same ultraviolet and infrared absorptive glasses, their color tones are important. For example, green glass and blue glass are considered to be completely different commercial products. For example, it is actual that buildings that have been built are formed of similar color tones and that the color tones are also strictly managed, except an extremely special example in which a pattern is formed of color difference. There has also been a case in which raw materials that have not been problematic so far are also limited due to the increased interest to the global environmental problems as compared with the past. Furthermore, the property requirement for various materials has become strict. Thus, there has been a case of an extremely complicated condition in which raw materials and properties, which are usable for certain commercial products, cannot be used for other commercial products.
As mentioned above, the environment surrounding glass has greatly changed, and it is in a condition in which glasses satisfying the complicated requirement specifications have not been developed sufficiently. In particular, it is a social demand for the development of an ultraviolet and infrared absorptive greenish glass of a predetermined green color tone and of not using selenium as a raw material.
Patent Publication 1: Japanese Patent Examined Publication 5-27578
Patent Publication 2: Japanese Patent Unexamined Publication 6-321577
Patent Publication 3: Japanese Patent Examined Publication 6-88812
Patent Publication 4: Japanese Patent Unexamined Publication 4-310539
Patent Publication 2: Japanese Patent Unexamined Publication 4-46031
Patent Publication 2: Japanese Patent Unexamined Publication 9-208254